The present invention relates to a fastening arrangement of a door sill on the floor panel of a motor vehicle, and more particularly, to an arrangement with a welded connection provided between a welding flange on a longitudinal side of the door sill and an edge zone of the floor panel extending laterally next to it, which welded connection being distributed along the length of the door sill, comprises at least one run of spot welds.
In such a fastening arrangement which is used in series produced motor vehicles, the door sill is conventionally fixedly connected by a welded connection along its longitudinal direction with an edge zone adjoining the door sill. For this purpose, the door sill has a welding flange on its longitudinal side. The welding flange is welded to the edge zone of the floor panel by at least one run of spot welds distributed over the entire length of the door sill. This results in a relatively low-cost welded connection between the door sill and the floor panel which can easily be made by automatic welding machines.
Particularly in the case of an offset frontal crash with a small width overlap of the motor vehicle with another vehicle or other obstacle, however, in fastening arrangements of this type, the spot-welded connection can fail because of occurring forces. The problem generally exists in such an offset frontal crash that, as the result of the accident forces acting in the front in the area of a forward wheel house, the motor vehicle is acted upon by a torsional force about a vertical axis of the vehicle. As a result, very high superimposed forces act between the door sill arranged on the side of the impact and the floor panel connected therewith, because the door sill arranged on the side of the impact is very decelerated in its movement within a short time, while, in contrast, the floor panel is acted upon by a torsional force about the above-described vertical axis of the vehicle. The spot-welded connection, which connects the door sill with the floor panel, is therefore stressed excessively particularly by tension forces, whereby the run of spot welds rips open, starting from the rearward end of the welded connection, in the direction toward the front, and the floor panel detaches from the door sill.
A bearing structure for a motor vehicle is shown in DE 40 08 703 A1 which has a relatively stiff supporting member and an adjoining thin-walled metal sheet. There, the supporting member has a so-called welding flange by way of which it is connected with the metal sheet. In order to prevent a destruction of the connection between the supporting member and the metal sheet in the event of impact-caused tension peaks, for example, in the event of a side impact, and in order to permit a uniform and large-surface introduction of force into the metal sheet, one or several projections are molded to the welding flange. The projections are connected with the metal sheet by welding. These measures are, however, not provided and suitable for avoiding particularly a tearing-off of the floor panel from the door sill. In addition, the construction of the welding flange with projections requires very high manufacturing expenditures.